This invention pertains generally to monopulse radar receivers in guided missiles, and particularly to an improved monopulse first detector array for a receiver in the millimeter wavelength band for use in seeker applications.
It is known to those of skill in the art that when monopulse radar techniques are employed, the radar receiver must separate the sum and difference signals to process and convert the monopulse information contained therein. Using a typical waveguide multimode horn feed, a fundamental frequency waveguide monopulse network is used to resolve the radar return into monopulse sum and difference channels containing the appropriate sum and difference signals. The three millimeter wavelength monopulse channels are then converted to an intermediate frequency (I.F.) using available waveguide mixers. An R.F. (radio frequency) waveguide approach to implementing the monopulse arithmetic network is large and requires precision machining or electroforming. Therefore, at millimeter wavelength frequencies, monopulse processing may be performed at an intermediate frequency in lieu of monopulse processing done at radio frequency (which is comparatively more tolerancesensitive and costly). In tactical weapons cost is of great concern. This is especially true for expendable weapons such as guided missiles. The use of a waveguide medium to process and convert the monopulse information is not a practical low cost solution suitable for high volume production. Monolithically constructed arrays for performing monopulse detection provide a more suitable alternative. Semiconductor processing techniques ensure mixer diode characteristics which are better and more repeatably matched. Therefore, more consistent electrical performance and lower production costs may be achieved.